(Still, there are tricky cases where you could believe one of two incompatible things, in such a way that picking one of them makes it true and the other false. In such cases, you should pick one that, if true, is more preferable than the alternative. Epistemic decisions given by the criterion of correctness are under-determined, in which case one should turn to the overall decision problem, and in some cases it might be better to believe even incorrect things.)
Upvoted for this.
No: there’s such a thing as epistemic rationality, and it’s the default referent when the phrase “rational belief” is used.
(Still, there are tricky cases where you could believe one of two incompatible things, in such a way that picking one of them makes it true and the other false. In such cases, you should pick one that, if true, is more preferable than the alternative. Epistemic decisions given by the criterion of correctness are under-determined, in which case one should turn to the overall decision problem, and in some cases it might be better to believe even incorrect things.)